Bluetooth: drop HCI device reference before return

Call hci_dev_put() to decrement reference count of HCI device hdev if
fails to duplicate memory.

Fixes: 0b26ab9d ("Bluetooth: AMP: Handle Accept phylink command status evt")
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>